diff --git a/common/src/main/java/org/conscrypt/ConscryptEngine.java b/common/src/main/java/org/conscrypt/ConscryptEngine.java
index 2296b90fb..bf3d1c844 100644
--- a/common/src/main/java/org/conscrypt/ConscryptEngine.java
+++ b/common/src/main/java/org/conscrypt/ConscryptEngine.java
@@ -1681,7 +1681,13 @@ private void closeAndFreeResources() {
     @SuppressWarnings("deprecation")
     protected void finalize() throws Throwable {
         try {
-            closeAndFreeResources();
+            // If ssl is null, object must not be fully constructed so nothing for us to do here.
+            if (ssl != null) {
+                // Otherwise closeAndFreeResources() and callees expect to synchronize on ssl.
+                synchronized (ssl) {
+                    closeAndFreeResources();
+                }
+            }
         } finally {
             super.finalize();
         }